Aside from being used in tires, rubber is used in a variety of other parts for automobiles, and other motorized vehicles and machines. In those environments, the components made from rubber have to withstand exposure to different chemical environments, such as oil, water, air or ozone, without losing the mechanical properties required for their intended use over a wide range of operating temperatures.
Hydrogenated nitrile rubbers, which have good heat-aging resistance and resistance to chemicals as well as suitable mechanical properties, are used in mechanical parts for performance in physical environments such as automobiles. However, the use of hydrogenated nitrile rubbers in some applications is limited by their relatively high cost.
Blends with other elastomers such as NBR, ECO, EPDM, CR, CPE, and the like have been considered. For example, U.S. Pat. No. 5,612,418 describes blends of a partially hydrogenated nitrile rubber and a polyacrylate elastomer. In general, some compromise of physical properties, especially heat resistance, must be made in such elastomeric blends. An important requirement for those blends is occuring between the elastomers to maintain key thermoset type properties, e.g., elevated temperature compression set resistance.
Also, in the prior art, attempts to combine the use of thermoplastic resins with rubbers have focused on using the rubbers as modifiers for the thermoplastic resins, in proportions such that the rubbers are dispersed as discrete particles, which may be partially vulcanized, in a matrix of the elastomers. For example, thermoplastic resins thus modified with hydrogenated nitrile rubbers are known. However, those compositions are not suitable for applications for which rubbers are usually used. In other words, such rubber-modified elastomers do not have sufficient rubber-like properties.